The present disclosure relates generally to turbine engines and, more specifically, to systems and methods of controlling rotor blade clearance in a centrifugal compressor of a gas turbine engine.
Known turbine engines experience several different phases of operation including, but not limited to, start-up, warm-up, steady-state, shutdown, and cool-down. In at least some of such known gas turbines, clearances between rotor blades and inner surfaces of the surrounding seal members are controlled to facilitate improving operating efficiency. Such clearances generally vary as the gas turbine transitions from one operational phase to another. More particularly, each operational phase has different operating conditions associated with it, such as temperature, pressure, and rotational speed, which will induce changes in the clearances between turbine and compressor components, including static and moving components within the gas turbine.
In at least some known gas turbines, the clearances between the rotor blades and the seal members are also controlled to prevent contact-related damage therebetween as the gas turbine transitions between operational phases. For example, in at least some known gas turbines, cold, or assembly, clearances are set to be no larger than required for steady-state operation to account for thermal and mechanical differences in the gas turbine when transitioning between phases of operation. Moreover, as described above, turbine efficiency depends at least in part on the clearance between tips of the rotating blades and seal members coupled to the surrounding stationary components. If the clearance is too large, enhanced gas flow may unnecessarily leak through the clearance gaps, thus decreasing the gas turbine's efficiency. Many known gas turbines include variable clearance mechanisms in the high-pressure turbine section or the low-pressure turbine section. However, it is generally difficult to implement clearance control systems in other sections of the turbine due to the complex geometry of the components.